Tab-complete issues with bash integration

[dundalek]

On a fresh install that only includes bash (without other shell) tab-complete does not work in certaion situations:

• global programs bas [TAB] does not expand to bash
• path starting with tilde ls ~/ [TAB]
• local executables, eg chmod +x abc, then ./a [TAB]

[dundalek]

It seems the issue is with the underlying script that extracts completions from bash. Following commands return nothing.

$ bash resources/completion/completion.bash "bas"

$ bash resources/completion/completion.bash "ls ~/"

I am not sure how to tweak it, so maybe we should just put a recommendation into docs to install zsh or fish in order to get good completion.